Environmental monitoring in Vikkilen, Grimstad, in 2018 – two years after sediment remediation actions

Summary

In 2016, remediation of contaminated sediments was undertaken in Vikkilen, outside AS Nymo's harbour area. The capped sediment area was heavily contaminated with polycyclic aromatic hydrocarbons (PAH) and tributyltin (TBT). On behalf of AS Nymo, NIVA has carried out monitoring of the effects from the measures taken. In 2018, common periwinkle was investigated for effects that could be due to exposure to TBT, which is toxic to aquatic organisms and which also has hormone disruptive effect on snails. Monitoring of pollutants in blue mussels from Vikkilen was also carried out. The results of the study show that the common periwinkle have no visible signs of effects due to exposure to TBT. There has been a significant reduction in the concentration of TBT in common periwinkle in Vikkilen since sediment measures were taken. There has also been a significant reduction in the concentration of PAH compounds and TBT in blue mussels in Vikkilen from 2016 to 2018. The significant improvement in the concentration of PAH compounds and TBT in blue mussels shows that the water quality in Vikkilen has improved during the two years since measures were taken outside AS Nymo.